1. Field of the Invention
The present invention relates to a safety wheel assembly. More specifically, the invention provides a safety wheel assembly structured to permit venting of air pressure within the tire if the wheel is improperly disassembled while an inflated tire is mounted on the wheel. The invention further provides a method of venting air pressure within the tire upon improper disassembly of the wheel.
2. Description of the Related Art
Multi-piece wheels having a rim with an inner bead retaining flange and a detachable outer bead retaining flange are commonly used to facilitate mounting tubeless tires on the wheel. Such wheels are particularly useful for mounting run flat inserts within tubeless tires. The tire and any desired run flat insert may be mounted on the rim with the outer retaining flange removed. The outer retaining flange may then be installed, and the tire inflated to the appropriate pressure.
The rim components of a two-piece wheel are typically secured together using a plurality of circumferentially spaced bolts, and are also secured to a vehicle using a plurality of circumferentially spaced threaded rods passing through a disc portion of the rim, and having lug nuts secured thereto. On occasion, an individual wishing to remove the wheel from a vehicle will begin removing the bolts holding the rim and outer retaining flange together instead of removing the lug nuts. When most of the bolts are removed, there is a danger that the few remaining bolts will fail, so that the air pressure within the tire propels the outer retaining flange towards the individual disassembling the wheel with significant velocity, resulting in a risk of injury or possibly even death to the individual.
Numerous patents propose solutions to this problem. For example, U.S. Pat. No. 2,428,551, issued to F. W. Burger on Oct. 7, 1947, discloses a safety wheel. The wheel includes a rim upon which the tire is mounted, and a bead locking ring fitting around the outer edge of the rim for securing the outer edge of the tire onto the rim. The bead locking ring is slidably mounted to the rim so that, when the tire is inflated, it will push the bead locking ring outward, resisting access to the bolts securing the bead locking ring to the rim. It is necessary to deflate the tire to slide the bead locking ring inward to gain access to these bolts. Such a wheel would not work with a run flat insert, because a run flat insert must securely hold both beads of the tire between itself and the opposing bead retaining flanges of the wheel. A run flat insert would therefore resist movement of the bead locking ring.
Several patents disclose wheel assemblies intended to vent air pressure from the tire if improper disassembly of the wheel is attempted. For example, U.S. Pat. No. 4,481,997, issued to D. S. Strader on Nov. 13, 1984, discloses a tire and rim combination with a safety insert. The rim includes an inner rim segment having an inner bead retaining flange, and defining a plurality of air bleed channels about 45 degrees apart. The wheel mounting disc is integral with the inner rim segment. An outer rim segment including an outer bead retaining flange is bolted to the inner rim segment, with a resilient O-ring seal therebetween. If disassembly of the wheel is attempted while the tire is inflated, compressive force on the sealing O-ring is removed, thereby permitting air to vent from the tire through the air bleed channels. This patent also discloses a run flat safety insert having an inner band extending around the rim base, and having projecting outboard and inboard edges for engaging the beads of the tire, clamping the beads against the bead retaining flanges. A plurality of axially extending ribs project radially inwardly from the bands, engaging the inner rim. An outer ledge is mounted coaxially with the inner band by a circumferential array of support struts. The outer ledge defines a recess around its circumference. A container of non-water base liquid lubricant is mounted within this recess. In the event of a ruptured tire, this container will engage the inner surface of the tire. The outer surface of the outer ledge is roughened with microscopic pockets for retaining lubricant.
U.S. Pat. No. 4,823,854, issued to R. E. Payne et al. on Apr. 25, 1989, discloses a safety insert for a safety tire. The tire includes an inner rim and an outer rim that are bolted together around their circumference, with a resilient O-ring seal therebetween. Air bleed passages are defined between the inner rim and outer rim segment so that, if the bolts holding the inner rim and outer rim segments are removed while a tire is inflated, air will be permitted to bleed out of the tire through the air bleed passages before all of the bolts are removed. The run flat insert includes a sheet metal base defining a pair of outer edges depending inward towards the rim, and an elastomeric trim around its outer surface. If the tire is deflated, pressure on the tread will push the outer edges outward, thereby securing the deflated tire between the outer edges of the run flat insert and the rim.
U.S. Pat. No. 4,836,261, issued to J. B. Weeks et al. on Jun. 6, 1989, discloses take-apart wheel assembly for use with a tubeless tire. The assembly includes an inner rim, an outer rim, and a disc. The disc and inner rim are welded together, and the outer rim is bolted to the disc. The disc defines a plurality of air bleed passages around its circumference. If an individual improperly begins removing the nuts holding the outer rim to the disc while a tire is inflated, the seal between the inner rim, outer rim, and disc will be broken, so that air will bleed out through the air passages before all of the nuts are removed. The same wheel construction is disclosed in corresponding European Patent Application No. 0 284 507 A2, published on Sep. 28, 1988. U.S. Pat. No. 5,215,137, issued to J. B. Weeks et al. on Jun. 1, 1993, discloses a safety tire and take-apart wheel assembly. The assembly includes an inner rim and an outer rim to which a disc is welded. The inner rim and outer rim are bolted together with an O-ring therebetween for providing an air seal. If bolts are removed from the wheel assembly while the tire is inflated, the outer rim will flex outward to break the air seal and allow the tire to deflate before all of the bolts are removed or fail. The length of the bolts is sufficient so that the inner and outer rims are separated sufficiently for air venting to occur before the nuts are completely removed from the bolts. A run flat safety insert is carried by the wheel assembly inside the tire. The air inflation opening is located in the outer rim portion, thereby providing greater room for the wheel brake system. The valve mounting struction includes a connector sleeve having insufficient size for passage of an inflation valve customarily provided on an inner tube, thereby resisting use of an inner tube within the tire. If an inner tube were used within the tire, the safety venting feature would prevent air from exiting the tire if the wheel were disassembled while the tire was inflated.
U.S. Pat. No. 5,215,137, issued to J. B. Weeks et al. on Jun. 1, 1993, discloses a safety tire and take-apart wheel assembly. The assembly includes an inner rim and an outer rim to which a disc is welded. The inner rim and outer rim are bolted together with an O-ring therebetween for providing an air seal. If bolts are removed from the wheel assembly while the tire is inflated, the outer rim will flex outward to break the air seal and allow the tire to deflate before all of the bolts are removed or fail. The length of the bolts is sufficient so that the inner and outer rims are separated sufficiently for air venting to occur before the nuts are completely removed from the bolts. A run flat safety insert is carried by the wheel assembly inside the tire. The air inflation opening is located in the outer rim portion, thereby providing greater room for the wheel brake system. The valve mounting structure includes a connector sleeve having insufficient size for passage of an inflation valve customarily provided on an inner tube, thereby resisting use of an inner tube within the tire. If an inner tube were used within the tire, the safety venting feature would prevent air from exiting the tire if the wheel were disassembled while the tire was inflated.
U.S. Pat. No. 6,315,366, issued to C. C. Post et al. on Nov. 13, 2001, discloses a safety wheel assembly having an inner rim, an outer rim, and a disc within the outer rim. The disc is joined to the inner rim by a single weld passing around the circumference of the disc. A series of bolts joins the outer rim to the disc. The removable outer rim facilitates installation of a tire and/or run flat insert onto the rim. An elastomeric seal is located between the inner rim, outer rim, and disc. In the event that the bolts holding the outer rim to the disc are loosened, the airtight seal formed the elastomeric seal will be broken, permitting air to exit the tire past the elastomeric seal prior to the complete removal of the nuts from the bolts.
In the experience of the present inventors, wheel designs such as those described above may fail to vent air pressure from the tire if the tire is improperly disassembled, creating a risk of injury when the last few remaining bolts holding the wheel together fail. The wheel assembly bolts will typically be installed and removed in a star pattern, so there will rarely be one side of the outer retaining flange that is completely unsupported, with no resistance to deforming and permitting air to bleed out.
U.S. Pat. No. 5,343,920, issued to J. M. Cady on Sep. 6, 1994, discloses a wheel assembly with flange securing and pressure relieving means. The assembly includes a rim and an outer flange bolted to the rim. An air passage extends from the interior of the tire to the opening through which the nut securing the outer flange to the rim passes. An O-ring is located between the nut and the inner flange, thereby providing an airtight seal over the air passage. Upon loosening of the nut, the airtight seal is broken, and air is permitted to vent from the tire.
One-piece wheels are sometimes used to avoid the disadvantages of a two-piece wheel. However, such wheels are difficult and expensive to manufacture, and may, for example, require as much as 1,200 pounds of aluminum to make a wheel weighing about 100 pounds.
Aluminum is a preferred material for manufacturing a wheel due to its combination of strength and light weight. Presently available steel wheels may weigh as much as 240 pounds, and require two individuals to remove from a vehicle. Additionally, if these wheels are used on an amphibious vehicle, the affect on buoyancy will be negative.
Several other patents disclose various wheel designs. For example, U.S. Pat. No. 512,619, discloses a take-apart wheel assembly, having no means for venting air pressure if the wheel is disassembled while the tire is inflated.
U.S. Pat. No. 2,576,736, issued to C. L. Watkins on Nov. 27, 1951, describes a wheel rim having a removable retaining band. No means for venting air pressure within the tire if the retaining band is removed while the tire is inflated are disclosed.
U.S. Pat. No. 2,802,508, issued to W. S. Brink on Aug. 13, 1957, discloses a truck rim design. The rim is intended for use with truck tires operated at lower than usual inflation pressure during movement through mud, sand, snow, and soft soil. This patent does not disclose a means of venting air from a tire if the wheel is disassembled while the tire is inflated.
U.S. Pat. No. 2,893,784, issued to T. C. Delker on Jul. 7, 1959, discloses a co-rotating dual wheel construction. Although the wheels have a two-piece rim design, there is no disclosure of any feature that would permit air within the tires to ventilate if the wheel was disassembled with the tire inflated.
U.S. Pat. No. 3,880,219, issued to W. E. Mitchell on Apr. 29, 1975, discloses a vehicle wheel. The wheel includes a flat base mounting for a tire, so that the tire beads cannot escape from the rim as they could in the case of a well base rim if the tire becomes deflated. The wheel is made from an inner rim, an outer rim, and a disc. A rubber O-ring fits between the inner rim and the outer rim to prevent leakage of air therethrough. This patent does not disclose any means of venting air from the tire if the wheel is disassembled with the tire inflated.
U.S. Pat. No. 3,882,919, issued to C. C. Sons, Jr., et al. on May 13, 1975, discloses a safety rim. The rim includes a base having an inner flange supported against a rim base lip, and an outer flange supported against the lip of a bead seat band. The outer flange and bead seat band are secured to the base by a lock ring, which is retained in position by locks threadedly secured to the base. Air passageways are provided for venting air from the tire if inflation of the tire is attempted when the lock ring and blocks are properly installed.
U.S. Pat. No. 4,165,177, issued to S. Sano on Aug. 28, 1979, discloses a device for joining surfaces of a split rim and a wheel. No safety venting device is disclosed.
U.S. Pat. No. 4,327,791, issued to D. S. Strader on May 4, 1982, discloses a safety tire and wheel assembly. The wheel includes a disc welted around its circumference to an inner rim segment. An outer rim segment is removably mounted to the inner rim segment by a plurality of nuts secured to threaded studs welded to the disc. The run flat insert includes a base having an eye-shaped cross section. A band surrounds the base with U-shaped bearing elements between the band and the base. The band is thereby permitted to slide with respect to the base.
U.S. Pat. No. 4,369,826, issued to V. P. Hendrickson on Jan. 25, 1983, discloses a multi-piece wheel structure. The wheel structure includes a rim having an inner bead retaining flange, and an outer bead retaining flange held in place by a locking ring. An air sealing ring is disposed within a channel in communication with the inflation valve, inside the locking ring. If the locking ring is not properly installed, the air sealing ring will be biased into the usual location of the locking ring, thereby resisting inflation of the tire by permitting air to pass through this channel, back outside the tire. This patent was based on International Application No. PCT/US81/00091 (Publication No. WO 82/02518), published Aug. 5, 1982.
U.S. Pat. No. 4,466,670, issued to Y. Kaji on Aug. 21, 1984, discloses a three-piece wheel for vehicle tires. No method of venting the air from the tire if the wheel is partially disassembled while the tire is inflated is disclosed.
U.S. Pat. No. 4,997,235, issued to M. Braungart on Mar. 5, 1991, discloses a two-piece wheel rim having increased disc area in proportion to the overall diameter of the rim for the purpose of providing a more light-weight apparatus.
U.S. Pat. No. 5,000,241, issue to T. C. Patecell on Mar. 19, 1991, discloses a unitary bead lock and run flat roller support ring for pneumatic tires on two-part wheels. The support ring includes a central portion and a pair of outwardly extended flanges for engaging the beads of the tire. The run flat assemblage surrounds the center portion of the ring.
U.S. Pat. No. 5,018,566, issued to L. Thoni on May 28, 1991, discloses a multi-part bolted steel rim. No means for venting the air in the event that the rim is disassembled while the tire is inflated is disclosed.
German Patent Application No. 37 38 009 A1, published on May 24, 1989, discloses a wheel having an inner rim within an outer rim bolted thereto, and a seal therebetween.
U.K. Patent No. 325,700, issued to W. Marx on Feb. 27, 1980, discloses a take-apart rim for the wheels of vehicles. No means of venting air pressure within a tire if the wheel is disassembled with the tire inflated is disclosed.
Various take-apart wheel assemblies are disclosed in Swiss Patent No 348,883, issued Oct. 31, 1960; German Patent Application No. 41 41 868 A1, published Jan. 14, 1993; German Patent Application No. 24 35 044, published on Feb. 20, 1975; French Patent No. 602,621, published Mar. 23, 1926; French Patent No. 626,258, published in Sep. of 1927; and French Patent No. 1,141,234, published Aug. 28, 157.
Accordingly, there is a need for a multi-piece wheel having less weight than existing wheels. There is a further need for a multi-piece wheel capable of receiving a run flat insert while also providing a reliable and safe means of venting air should the inflated tire/wheel assembly be improperly disassembled.